I just pulled the rear from a 71-72 GS 350 4 speed car. It looks like the rear has P2 0111 stamped into it. Now the P is cut off at the bottom so it could be a P, B, R or ? I got it to replace the rear in my 70 skylark to get a posi and better gears easier.
Make sure there isn’t any other letters to the left. There might be a space. R2 is an Oldsmobile code for 2:56 non-posi.
Yep... was thinking the same deal . Tons of R2 rears out there ...I have had MANY..... 71 - 72 Buick codes do not even use numbers in their code. I would say that was swapped at some time. They are all 'L' something most of the time sorry to say.
Well dam... So trying to find the up side. Are the R2 axles any good. Are they easier to find a posi for. Will it live up to a mild 455.
You just have to buy all the parts for the rear. Only the axles and the yoke will be reusable. Posi gears and bearings will need to be purchased. ALL the housing are the same. All 10 bolt 8.5 are that...8.5 10 bolts... You can install any ratio any type of posi etc.
The 8.5” 10-bolt is one of the best rears ever built. Plenty of parts available,and a great design. Remove the cover,drain the oil,and see exactly what you have inside. There will be a series of numbers along the outside edge of the ring gear. That will give you the ratio.
Remember you will have a driveshaft length issue from a 1970 rear being in there. 10 bolt 8.5 pinion snouts are longer so double check that drive shaft length after installing the rear in the car. 2 tight and you will bottom out in the trans cause vibration issues and excessive wear to the tail shaft bushing and even internal transmission parts. TOO short is not good either... as the same thing will happen hanging too far out on the end of the output transmission spline. Take care, Take pics and post if you need help figuring out your numbers Brian mentioned. Jim
It looks like the 2.56 open gears are in tact So I will end up holding off until after I put the 455 in and will swap the rear when I go from the th350 to the 400 since that will require a different drive shaft length any way.
SOUNDS LIKE A PLAN. You can blast it and build it all up and then just swap it right in. You can do all this and it will be a nice hobby piece to fix. Jim
